A NATION CHALLENGED: MYSTERY; U.S. Denies Taliban Claim That Dead Man Was American

The American Embassy in Islamabad said today that a man who the Taliban announced had died in a hospital in Afghanistan was not an American citizen, as the Taliban had asserted.

The spokesman at the embassy, Mark Wentworth, said the embassy had ''made a determination that he is not an American citizen.'' Mr. Wentworth said he had no information on the nationality of the man whom the Taliban had described as John Bolton of California.

A senior Taliban official, Amir Khan Muttaqi, said the man had been arrested when he crossed the border from Pakistan at Spin Boldak after having asserted that he was a relief worker.

The Taliban ambassador to Pakistan, Mullah Abdul Salam Zaeef, said that the man was a spy and that he was carrying a satellite phone and a map when arrested. The International Committee of the Red Cross, which supports the main hospital in Kandahar, said the Taliban had given them personal information that was passed to the United States authorities to trace the man's relatives. A Red Cross official declined to release the name of the man but said the information was credible enough to search for his kin.

A man named John Bolton stayed here at the Marriton Hotel, which is managed by Afghans, for five months and left recently, a hotel worker said. The man had an American passport and a Pakistani identity card, the worker added. The man could have easily acquired a fake Pakistani identity in the city bazaar.

The Taliban said the man they held in custody became sick and was taken to a hospital. Refugees from Kandahar in recent days described the main hospital there as having no staff and little medicine. Civilians and Taliban fighters injured in the bombing of Kandahar have been taken here for treatment.

According to a local Pakistani report, Taliban officials said the American had initially introduced himself as Maj. Mazhar Ayub, and described himself as a journalist.